OK found out, what the deal was.
It was the left side iwe, i did all the test necessary and everything checked out, what the problem is, somebody down the line, had striped one of the three bolts holding it to the steering knuckle, i noticed that when i replaced that side's axle months ago, but didn't think it would be the cause.
Well sure enough, when i apply vacuum while 4 hi is engaged, the noise isn't there.
But when i take away the vacuum, and drive in 4hi it comes back.
So looks like a new iwe and a new bolt is in store.

 

NOT! thought i had the fix, but sadly it wasn't, Ive replaced the CV axle on both sides, the iwe on the drivers side, then the hub today on the drivers side... and guess what.... the damn noise is still there.
So i finally grew a brain and put the truck on stands and let her rip, what i found is the front diff is moving up and down depending on what gear your in.
So I'm thinking the bushings are shot on the front diff, because it moves way to much.

 

https://www.f150online.com/forums/ar...then-some.html

check this out might give you something
I'm thinking it might me the solenoid

 

This may be a real long shot but, do you have limited slip on the front axle?
I had a 78' Torino GT with limited slip rear and just going around curves in the mountains I would get a popping glunking sound. They told me the clutches in the posi were to tight, they readjusted them and that took care of it. Just a thought and maybe a solution.
Good Luck!

 

Black out 07 . I have the same problem . Ive replace the hub (wheel bearing ) cause the teeth were worn a little where the actuator goes over it . I also replaced the actuator i goes into 4x4 but when I tramp on the gas it also gives me a loud snapping noise on the driver side. Same noise and i am out 500 bucks and still have the same problem . All I have left now is to replace the cv shaft and hopefully that works.

 

Wait check your bushings on your front diff.
Put your truck on stands, and have somebody keep putting it in forward and reverse and watch the travel of the front diff.Has to be in 4wd tho.
I think I'm chasing the same noise as you, Ive replaced u joints,both axles,iwe(drivers),hub and its still making a click clank noise in forward and reverse under heavy acceleration, it also makes the same noise turning in 4wd and yes that includes gravel and snow.
I need somebody to help me out and check to see how much travel the front diff is supposed to have, i mean mine moves at least an inch up and down, and i even can move it with a pry bar, and i don't think i should be able to do that.

 

ok i think i found out the problem i cleaned the vaccuum lines going to each actuator and went out for a drive in 4x4 to a gravel road took off front a dead stop to the floor for about 300 feet and not once did it make the noise . Gonna try it for a few days and see will post results after if this was the problem . BTW DO NOT clean the vaccuum line with the ckeck valve on it it goes to a vaccuum box behind your battery and it will blow apart, also disconnect the hoses at the actuators before cleaning .

 

savagemonte,
Your truck is making the noise in both 2wd and 4wd?
My front axle seemed like it moved/twisted way to much to be right, It would move maybe 1.5" out of place if i remember right. But it only did it at a certain point like every half or full revolution of the tire. This led me to believe it was a bad cv joint binding up trying to turn, and when it wouldn't turn the front axle was forced to twist until the bound up cv came free.

I didn't see anything that the axle would have hit in order to make that loud pop noise though, not saying it couldn't still be the cause of the noise.

I need to go out and try my 4wd again to make sure the noise really is fixed.

 

Mine makes the noise in 4wd only.
Blackout07 does your truck have a lift on it? Mine has a 6 in lift and the back bolt that holds the rear part of the diff seems to move at least 1 in when load is applied to the drive shaft.
But I think the noise is coming from the diff hitting the frame or that bolt, I just know the diff shouldn't move that much.

 

I'm sorry the rear bushing on the front diff allows way to much movement.

 

Mine is leveled 2" with bilstein shocks right now. My front axle assembly was moving at least an inch just like yours is when it was making the pop noise. I haven't checked it since the new cv axles, I wont be able to check it until I go home for xmas break where all my tools, jacks, blocks, etc are.

Have you priced new bushings for it?

 

Yeah I got three new ones on the way.
If you go to ford you'll pay about $30.00 per bushing.
But if you go to fordpartsgiant.com you can get them for around $12.00, I just ordered mine last night.

 

great price thanks for the heads up. Please post back your results on it!! Hope it does the trick

 

Me to, I'm getting tired of not being able to solve this.

 

The noise is embarrassing offroad! lol